Software Architect's Handbook

No downtime

Applications today are expected to be available at all times, with no downtime. It has always been a goal to minimize downtime, but the days when it was acceptable to have a small maintenance window in which an application was not available are over.

Complex software systems will have failures and should be designed to expect failures to occur. Cloud-native applications are designed for failure and keep fault tolerance in mind so that they can recover rapidly and minimize downtime. If a physical server fails unexpectedly or is taken down as part of planned maintenance, a failover system will redirect traffic to a different server. Software components should be designed so that they are loosely coupled, such that if one fails, ...